The present invention concerns a method of manufacturing pistons and components thereof, piston heads for example, especially intended for internal-combustion engines.
German A 3 801 847 discloses a method of manufacturing pistons for internal-combustion engines, each piston being provided with at least one metal reinforcement. The reinforcement, of a material with open pores, is heated and introduced into a heated die. A prescribed amount of aluminum or aluminum alloy is injected into the die. A plunger is introduced into the die, compressing the cooling melt. The compressed melt flows around the reinforcement and fills both the piston mold and the reinforcement's pores. Once the melt has hardened, the piston is removed from the die along with the reinforcement and machine finished.
A piston especially intended for internal-combustion engines is known from German A 19 935 410. This piston features a shaft with a bore for a bolt and an adjacent annular field. Webs extend from the bore toward the annular field and/or toward the end of the shaft remote from the field. Pistons of this type are preferably cast.
German A 3 222 582 describes a method of manufacturing a base for a multiple-component piston, especially intended for large diesel engines. The center of the base is domed and surrounded by a shoulder and has an interior hub. The shoulder accommodates piston rings and rests against a separate piston shaft, onto which the hub can be screwed and/or welded. In this method a bowl with an area that matches the shape of the piston's center and has a surrounding collar is in an initial shaping step forged from a heat-resistant steel. The shoulder and the hub are then in a subsequent shaping step forged out of the collar. This approach, which involves forging axially in terms of the piston's base, however, allows only contours with prescribed wall thicknesses, especially radial wall thicknesses, and the product is heavy and requires a lot of material.
German A 3 222 582 describes a method of manufacturing a base for a multiple-component piston, especially intended for large diesel engines. The center of the base is domed and surrounded by a shoulder and has an interior hub. The shoulder accommodates piston rings and rests against a separate piston shaft, onto which the hub can be screwed and/or welded. In this method a bowl with an area that matches the shape of the piston's center and has a surrounding collar is in an initial shaping step forged from a heat-resistant steel. The shoulder and the hub are then in a subsequent shaping step forged out of the collar. This approach, which involves forging axially in terms of the piston's base, however, allows only contours with prescribed wall thicknesses, especially radial wall thicknesses, and the product is heavy and requires a lot of material.